WO1999036285A2 - Multispeed powershift transmission - Google Patents

Abstract

A mechanical power transmission system for an engine or motor driven vehicle includes an input transmission (23, 34, 41), a compound planetary transmission (27, 42, 53, 69), and an output transmission (30, 33, 48, 50, 64). The compound planetary transmission includes two inputs (R shaft, S shaft) and two outputs (S2, C). The input transmission has a single input (input shaft) connected to the engine or motor of the vehicle and two outputs (23, 34) connected to the two inputs of the planetary transmission. The output transmission includes two inputs (S2 shaft, C shaft) connected to the two outputs of the planetary transmission and one output (output shaft) connected through suitable gearing to the wheels of the vehicle.

Description

MULTISPEED POWERSHIFT TRANSMISSION

Field of Invention

The present invention relates to a multispeed mechanical transmission with an optional hydrostatic attachment, useful in, but not limited to agricultural tractors.

Background of the Invention

The prior art is replete with various transmissions for agricultural tractors and the like. Multispeed transmissions having countershafts are widely used in the power train of tractor arrangements because a plurality of rotating clutch assemblies and associated gears can be positioned on parallel shafts to allow considerable flexibility in adapting them to different space requirements and "gear spacing".

"Gear spacing" is the ratio change between gears which produces the change in vehicle speed when the operator shifts to a different gear. The smaller this gear spacing the better the optimum engine speed can be matched to the optimum ground speed. The more gear selections that are available, the finer the gear spacing can be designed. However, the number of clutches and gears increases with added gear selections, increasing the cost, etc.

"Shift quality" is the operator's perception of how smoothly a transmission reacts when making a shift. Many factors affect shift quality, such as rapid changes in speed of elements with large inertia within the transmission, poor timing of the pressure control, large torque interruptions at heavy loads, large gear spacing, and most of all, the number of clutch "swaps" required from one gear selection to the next. (A single clutch swap is defined as the disengagement of one clutch and the engagement of another clutch to complete a shift.)

All currently manufactured powershift transmission have multiclutch swaps during some shifts in the operating range. It is difficult, if not impossible, to make multiclutch swaps smooth because during a shift, one or more of the engaging clutches opposes the direction of the shift. For example, in one typical transmission, during a triple clutch swap upshift from 6^th to 7^th gear, one of the clutches shifts up while the other two clutches shift down. Any sequence of clutch engagements will cause torque reversals. This effect is inherent in all multiswap shifts of current designs. Only single clutch swaps can be shifted smoothly by overlapping the engagement of oncoming clutch with the disengagement of the outgoing clutch.

There are special applications for the type of vehicle using the transmission described herein where exact speed control is important, such as trenching or certain planting and harvesting operations, among others. In many of these applications, most of the engine power is used to drive the mechanism of the towed attachment through the power take off (PTO) with only part of the power used for the forward motion of the vehicle. Here, transmission efficiency is of secondary importance, with the primary importance being the ability to vary the ground speed at small increments independently of the engine. In such cases, an continuously variable transmission is desirable. Continuous variability can be achieved, for example, through the use of hydrostatic units, in which case, transmission efficiency is sacrificed. Other continuously variable transmissions include electrical generator-motor sets or variable friction drives.

Two types of the continuously variable transmission are of interest:

1. Continuous variability from a certain minimum vehicle speed to the maximum vehicle speed with frill power transmission capability in one mode of operation, and continuous variability from zero to a certain low vehicle speed with maximum traction capability in another mode of operation. In the full power mode a means (such as a clutch) must be available to start the vehicle in motion at full load. As pertains to the present invention, this type will be called a partial continuously variable transmission (PCNT).

2. Continuous variability from zero to maximum vehicle speed with full power and maximum traction capability within a single mode of operation. As pertains to the present invention, this type will be called a frill continuously variable transmission (FCNT).

Summary of the Invention

It is the object of the present invention to provide the largest known number of gear selections with a given number of clutches. For example, current transmissions with 9 clutches provide between 16 and 18 speeds forward with 4 to 6 reverse speeds. A typical arrangement of the present invention provides 23 forward and 8 reverse speeds using 9

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SUBSTΓΠΠΈ SHEET (RULE 25) clutches as shown in Chart 3 and Figure 3. These five extra speeds allow a closer gear spacing.

It is a further object of this invention to provide a variety of transmission systems from which to choose for specific applications.

It is a further object of the present invention to provide single clutch swaps for all single step and double step shifts throughout the normal operating range. Single step means sequential shifts and double step means skipping a gear selection.

It is a fiirther object of the present invention to maximize the efficiency by keeping the number of gear meshes low. Also, the clutch sizes and speeds can be minimized for low losses.

It is a further object of the present invention to provide continuous variability of the type PCNT via an optional attachment. In this case, the present invention proposes the use of modulated clutches for starting the vehicle motion, thus allowing for the use of relatively small hydrostatic units.

It is a fiirther object of the present invention to provide an alternate transmission system with continuous variability of the type FCNT. A continuously variable transmission from zero to maximum vehicle speed is realized by making the hydrostatic units large enough for sufficient torque to start the vehicle motion.

It is a fiirther object of this invention to provide a compact transmission package using a unique gear, shaft, clutch and bearing arrangement.

General Description of the Basic Powershift Transmission

"Transmission" as used in this document is an arrangement of gears, shafts, clutches and bearings located in a housing for the purpose of transmitting rotational power, "input" meaning power absorbing, "output" meaning power delivering. The transmission system consists of an input transmission, a compound planetary system and an output transmission.

A compound planetary system is a planetary system consisting of at least two simple planetaries.( Fig. 5 ) There are two kinds of simple planetaries, the single and the double planetary. These are defined as follows.

A single planetary is comprised of a internal ring gear, a sun gear and a set of planets (usually three) which are rotatably mounted on sets of shafts anchored in a planet carrier. Each planet gear is in mesh with the ring gear and with the sun gear thus acting as an idler gear between the ring and the sun gear.

A double planetary is comprised of an internal ring gear, a sun gear and two sets of planet gears which are rotatably mounted on two sets of shafts each set of shafts being anchored in a planet carrier. One set of planets is in mesh with the ring gear and with the other set of planets which in turn is in mesh with the sun gear.

Another type of compound planetary system uses cluster planet gears. ( Fig. 6 ) Usually an equivalent planetary system of the first type described above can be constructed. The input transmission has one input member connected to the engine or motor and two output members each of which is selectively connectable to the input member by clutches through various gear ratios in forward and reverse. The output members are connected to the two input members of the compound planetary system.

The compound planetary system has two input members connected to the input transmission (as stated in the previous paragraph) and two output members connected to the output transmission.

The output transmission has two input members connected to two output members of the planetary system (as stated in the previous paragraph) and one output member connected to the rear and/or to the front wheel drive of the tractor. The output member is selectively connectable by clutches through various gear ratios to each of the two input members.

Various accessory drives can be included wherever convenient to the input and output transmission.

Description of One Typical Embodiment of the Basic Powershift Transmission

In what follows, a specific transmission system (shown in Figure 1 and Chart 1) is described. It is understood, however, that the invention is not limited to this specific example. The compound planetary system consists of one ring gear R, two sun gears, S_t and S_j, and one planet carrier C on which two sets of planets, Pj and P_θJ are rotatably mounted by two sets of shafts.

The input transmission of this system has two sets of three clutches. One set, denoted F, REN, and B, selectively connects the input shaft to the R shaft through various gears or it stops the R shaft. The other set, denoted f, rev, and b, selectively connects the input shaft to the S, shaft through various gears or it stops the S, shaft.

The output transmission has two sets of clutches. One set, denoted 1, 3, and 5, selectively connects the output shaft to the C shaft through three corresponding gear ratios. The other set, denoted 2, 4, and 6, selectively connects the output shaft to the S₂ shaft through three corresponding gear ratios.

The compound planetary systems shown on Figure 5 and in Line Diagram 1 A is incoφorated in Figures 1, 2, 3, 4, 1H, 2H and in the Layouts 2, 1H and 2H. It is comprised of a single input planetary P_; and a double output planetary P₀. The members of the two planetaries are connected as shown: The ring gear R of the planetary P_; is connected to the ring gear of the planetary P_θJ the carrier of the planetary P; is connected to the carrier C of the planetary P₀. The two input connections, R and S_l5 are attached to the ring gear and to the sun gear of the planetary P_;, respectively, and the two output connections, C and S₂, are attached to the carrier and the sun gear of the output planetary P₀, respectively.

The compound planetary system has the following characteristics:

1. The ratio of speeds of any two of the four members (two input and two output members) determines the ratio of speeds of all members to each other.

2. At a constant speed of one input member (the ring gear R), as the other input member (the sun gear Sj) is varied from a negative speed to zero to a positive speed, the speed of one output member (sun gear S₂) decreases and the speed of the other output member (planet carrier C) increases. (Of course, as the sun gear S_j is varied from a positive speed to zero to a negative speed, the speed of S₂ increases and the speed of C decreases.)

An alternate planetary system, equivalent to the one described above, is shown in Figure 6 and in Diagram IB. The first planet set P_; is made up of three cluster gears each having a gear on the left and a gear on the right. The gears on the left are in mesh with the ring gear R at the outside and with the first sun gear S, at the inside. The gears on the right are in mesh with the gears of the second planet set P₀. The second planet set P₀is also in mesh with the second sun gear S₂. Both planet sets, P_f and P₀ , are rotatably mounted to the same carrier C.

A second alternate planetary system is shown in Figure 7 and line Diagram lC. This compound planetary system is comprised of two single planetaries P_{ and P₀, each having a ring gear, a sun gear and planet gears rotatably mounted by sets of shafts in respective planet carriers. The members of the two planetaries are interconnected as shown: The ring gear of the planetary Pj is connected to the carrier of the planetary P₀ and the carrier of the planetary P; is connected to the ring gear of the planetary P₀. The two input connections, R and S_if are attached to the ring gear and to the sungear of planetary P_b respectively. The two output connections, C and S₂, are attached to the ring gear and to the sun gear of planetary P₀, respectively.

A third alternate planetary system is shown in line Diagram 2A. This compound planetary system is comprised of two double planetaries P_j and P_θJ each having a ring gear, a sun gear and planet gears rotatably mounted by sets of shafts in respective planet carriers. The members of the two planetaries are interconnected as shown: the ring gear of the planetary Pj is connected to the ring gear of the planetary P₀ and the carrier of the planetary Pi is connected to the sun gear of the planetary P₀. The two input connections, R and S^ are attached to the ring gear and to the sungear of planetary P_i5 respectively. The two output connections, C and S₂, are attached to the carrier and to the sun gear of planetary P₀, respectively.

A fourth alternate planetary system is shown in line Diagram 2B. This compound planetary system is comprised of two single planetaries P; and P₀, each having a ring gear, a sun gear and planet gears rotatably mounted by sets of shafts in respective planet carriers. The members of the two planetaries are interconnected as shown: The ring gear of the planetary Pj is connected to the ring gear of the planetary P₀ and the sun gear of the planetary P_; is connected to the sun gear of the planetary P₀. The two input connections, R and S_l5 are attached to the carrier and to the sun gear of planetary P_j, respectively. The two output connections, C and S₂, are attached to the ring gear and to the sun gear of planetary P₀, respectively. A fifth alternate planetary system is shown in line Diagram 2C. This compound planetary system is comprised of a double planetaries P_s and a single planetary P₀, each having a ring gear, a sun gear and planet gears rotatably mounted by sets of shafts in respective planet carriers. The members of the two planetaries are interconnected as shown: The ring gear of the planetary P_; is connected to the carrier of the planetary P₀ and the carrier of the planetary P; is connected to the sun gear of the planetary P₀. The two input connections R and S, are attached to the ring gear and to the sun gear of planetary P_j respectively, and the two output connections C and S₂ are attached to the ring gear and to the sun gear of planetary P₀ respectively

A sixth alternate planetary system is shown in line Diagram 3 A. This compound planetary system is comprised of a single planetaries P_; and a double planetary P_θJ each having a ring gear, a sun gear and planet gears rotatably mounted by sets of shafts in respective planet carriers. The members of the two planetaries are interconnected as shown: The ring gear of the planetary P_j is connected to the sun gear of the planetary P₀ and the carrier of the planetary P_j is connected to the ring gear of the planetary P₀. The two input connections R and S, are attached to the carrier and to the sun gear of planetary P_s respectively, and the two output connections C and S₂ are attached to the carrier and to the sun gear of planetary P₀ respectively

A seventh alternate planetary system is shown in line Diagram 3B. This compound planetary system is comprised of a single planetary P; and a single planetary P_θJ each having a ring gear, a sun gear and planet gears rotatably mounted by sets of shafts in respective planet carriers. The members of the two planetaries are interconnected as shown: The carrier of the planetary P_j is connected to the ring gear of the planetary P₀ and the sun gear of the planetary P_j is connected to the sun gear of the planetary P₀. The two input connections R and S, are attached to the carrier and to the sun gear of planetary P_j respectively, and the two output connections C and S₂ are attached to the carrier of the planetary P₀ and to the ring gear of planetary P_j, respectively.

An eighth alternate planetary system is shown in line Diagram 3C. This compound planetary system is comprised of a single planetaries P; and a single planetary P_θJ each having a ring gear, a sun gear and planet gears rotatably mounted by sets of shafts in respective planet carriers. The members of the two planetaries are interconnected as shown:

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SUBSTTΠΠΈ SHEET (RULE 26) The carrier of the planetary P_; is connected to the carrier of the planetary P₀ and the sun gear of the planetary P_; is connected to the sun gear of the planetary P₀. The two input connections R and S, are attached to the ring gear and to the sun gear of planetary P₄ respectively. The two output connections C and S₂ are attached to the carrier and to the ring gear of planetary P₀, respectively

A ninth alternate planetary system is shown in line Diagram 4A. This compound planetary system is comprised of a single planetaries P; and a double planetary P₀, each having a ring gear, a sun gear and planet gears rotatably mounted by sets of shafts in respective planet carriers. The members of the two planetaries are interconnected as shown: the carrier of the planetary P_; is connected to the carrier of the planetary P₀ and the sun gear of the planetary Pj is connected to the ring gear of the planetary P₀. The two input connections, R and S are attached to the ring gear and to the sun gear of planetary P_}, respectively. The two output connections, C and S₂,are attached to the carrier and to the sun gear of planetary P₀, respectively

In the following description power flow may be positive or negative.

The input transmission absorbs engine power through the input shaft, transmitting power selectively through two pairs of clutches to the two input members, S_t and R, of the compound planetary. The first pair of clutches is denoted f and F, and the second pair is denoted rev and REN.

The first pair of clutches is mounted on the input shaft to selectively drive the ring gear R through clutch F, via a gear set 34F to 42 , and to selectively drive the sun gear S_t through clutch f, via a gear set 23f to 53.

The second pair of clutches is mounted on the reverse shaft. This shaft is driven through a 41 to 41r gear set from the input shaft. The reverse shaft is located such that the 34Rev gear is in mesh with the 42 gear and the 23 rev gear is in mesh with the 53 gear. Thus, the selective engagement of the clutches REN and rev will respectively drive the ring gear R and the sun gear S_t in the opposite direction at the same speeds as the F and f clutches.

In addition to these two pairs of clutches, there are two clutches B and b. Engagement of B will stop the ring gear R and of b will stop the sun gear S The output transmission absorbs power selectively through two shafts S₂ and C. Power is transmitted through either one shaft or the other or through both shafts in certain proportions. The shafts of both S₂ and C have clutches mounted on them which in combination with the clutches mounted on the output shaft provide three selective gear ratios each from S₂ to the output shaft and from C to the output shaft. The even numbered clutches, 2, 4 and 6, selectively connect the S₂ shaft to the output shaft at certain ratios provided by the gear sets 16(2) to 64(2), 30(4) to 50(4) and 48(6) to 33(6), respectively. The odd numbered clutches, 1, 3 and 5, selectively connect the C shaft to the output shaft at certain ratios provided by the gear sets 16(1) to 64(1), 30(3) to 50(3) and 48(5) to 33(5), respectively.

To establish a connection from the engine to the output shaft of the output transmission either:

(1) Two input clutches and one output clutch must be engaged, or

(2) One input clutch and two output clutches must be engaged.

(1) Two input and one output clutches engaged:

Two input clutches are engaged, one driving the ring gear R at a certain ratio with respect to the engine, and one driving the sun gear Sj at a certain other or same ratio with respect to the engine, will establish a ratio of two members of the planetary system; also one input clutch F or REV driving the ring gear R with the sun gear S_t stopped (b engaged), or one input clutch f or r driving the sun gear Sj with the ring gear R stopped (B engaged), will establish a ratio of two members R and S_t of the planetary system. Then by Item (1) on page 4, the ratios of all members of the planetary system are established. Thus, the engagement of any one clutch (1, 2, 3, 4, 5, or 6) in the output transmission will establish an overall ratio from the input (engine) to the output of the transmission system.

(2) One input and two output clutches engaged:

Two output clutches engaged, with one of the clutches 2, 4, or 6 connecting the sun gear S₂ to the output shaft of the output transmission at a certain ratio, and one of the clutches 1, 3, or 5 connecting the carrier C to the output shaft at a certain other or same

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SUBSTΓΓUTE SHEET (RULE 26) ratio, will establish a ratio between S₂ and C. Again, by Item (1) on page 4, the ratios of all members of the planetary system are established. Thus, the engagement of any one input clutch, F or Rev, which connects the engine to the ring gear R, or any one input clutch for rev, which connects the engine to the sun gear S_h will establish a ratio from the engine to the output shaft of the transmission system.

Engaging the clutches as in either (1) or (2) above establishes a "gear" for the transmission system. The number of possible "gears" is the total number of possible combinations in (1) and (2). Thus,

F and rev combined with 6 output clutches = 6 forward "gears",

REV and rev combined with 6 output clutches = 6 reverse,

F and b combined with 6 output clutches = 6 forward,

REV and b combined with 6 output clutches = 6 reverse,

F and f combined with 6 output clutches = 6 forward,

REV and f combined with 6 output clutches = 6 reverse, f and B combined with 6 output clutches = 6 forward, rev and B combined with 6 output clutches = 6 reverse,

F at input combined with 9* combinations at output = 9 forward,

REV at input combined with 9* combinations at output - 9 reverse, fat input combined with 9* combinations at output = 9 forward, rev at input combined with 9* combinations at output = 9 reverse

* The 9 combinations at output are: 1-2, 1-4, 1-6, 2-3, 2-5, 3-4, 3-6, 4-5, 5-6.

Thus, there are 42 forward "gears" and 42 reverse "gears" possible in the transmission shown on Figure 1 and Chart 1.

In order to provide single clutch swap shifts, a certain sequence of clutch combinations for each "gear" is chosen, as shown on Chart 1, column 2. By selecting certain gear ratios for all gears in the system it is possible to provide reasonably equal geometric steps (1 l+or-2 % shown as % speed change in column 9 on Chart 1) from one gear selection to the next by choosing the sequence shown on the Chart 1. Note that some of the possible combinations of clutches are not used because they either provide redundant

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SUBSTΓΓUTE SHEET (RULE 26) speeds or they will not fall within the single clutch swap sequence. Thus, from the 42 possible combinations available only 33 are used.

The attached Chart 1 shows the various clutches engaged in each gear selection (column 2) with the corresponding speeds of each shaft in the typical transmission described. Note the clutch REV and the clutch B are considered optional at added cost. The "standard" transmission has only 27 speeds forward and 9 speeds reverse. The addition of the clutch REV will make these 9 speeds reverse redundant. Therefore, a 27 speed forward and 27 speed reverse will result by adding the REV clutch. The addition of the clutch B will add 6 forward and 6 reverse speeds. These 6 speeds are the creep option for applications at very low vehicle speeds.

General Comments on the Basic Powershift Transmission

Planetary systems, which exhibit the characteristics as described under Item 1 and 2 on page 4, may be currently in use or described in existing patents. It is the idea of this invention to combine a planetary system having these characteristics with an input transmission and an output transmission, each having a plurality of selectable gear ratios.

It is an additional idea to design the compound planetary system with two input means and two output means, to design the input transmission with one input and two output means and to design the output transmission with two input and one output means.

It is an additional idea to select from a number of planetary systems the one that is best for the particular application, depending on the speed range to be covered, the number of gear selections, manufacturing capabilities, space limitations, etc.

It is an additional idea of this invention to design the input transmission to provide two output means, each of which has a forward-reverse symmetry with or without a zero speed (lock) between forward and reverse. Thus there is an equal reverse gear ratio corresponding to every forward gear ratio for each of the output means which are selectively connectable to two input means of the planetary system. (It is understood, however, that this forward-reverse symmetry is not a requirement).

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SUBSTΓΠΠΈ SHEET (RULE 26) It is an additional idea of this invention to design the output transmission to provide two input means, each of which has several gear ratios connectable to the output shaft of the transmission system.

It is an additional idea to select the gear ratios in the planetary system such that the following differential equation is essentially* met:

R " = constant, with the constraint

Si ii - K ør, at -?, = 0 ,

* Note: Since all gear ratios are ratios of integral numbers the above equations may only be approximated.

where

S₂ is the speed of one output member of the planetary system,

r₂ is the lowest selectable gear ratio between the sun gear S₂ and the output shaft of the transmission system,

is the speed of the other output member of the planetary system,

r, is the lowest selectable gear ratio between the carrier C and the output shaft of the transmission system,

S_x is the speed of the input member of the planetary system, which is selectively connectable to the engine at one or more ratios in forward and reverse,

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SUBSTΓΓUTE SHEET (RULE 26) lζ is the speed of that input member of the planetary system, which is connected to the engine at a constant gear ratio through a clutch, which remains engaged during shifting in the normal operating range,

K is a constant calculated by the following equation:

Note: exp. means that the number in the second brackets is the exponent to the number in the first brackets.

where

H is the highest desired rated output speed of the transmission system,

L is the lowest desired rated output speed to be attained in the normal operating range (this is the range in which the clutch F remains engaged),

N₀ is the number clutches in the output transmission,

N_s is the number of clutches in the set which selectively connects the engine through gear ratios to the input member S_j.

It is an additional idea of this invention to make the geometric steps from one gear selection to the next equal to each other in a certain interval. For an odd number N_s of clutches connectable to the sun gear S_l5 this interval is from the gear in which two output clutches are engaged to the higher gear in which the sun gear S_x is stopped. (In the Chart 1, the step from the gear selection F 1 2 to F 2 f is equal to the step from the gear selection F 2 f to F 2 b. In the case of an even number of clutches connectable to the sun gear S_j, the interval is from the gear in which two output clutches are engaged to the first gear in which the direction of the speed of the sun gear S_j is changed. (In Chart 3, the step from F 1 2 to

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SUBSTΓΓUTE SHEET (RULE 26) F 2 f₂ is equal to the step from F, 2, f₂, to F, 2, f and equal to the step from F, 2, f_j, to F,

2, r,. Note that in the last step the direction of Sj is changed from f, to T_j). This choice of steps will provide the best compromise for gear spacing throughout the total range of the transmission system.

It is an additional idea of this invention to design the gear ratios in each branch of the output transmission such that a geometric progression results with the common ratio e al _{t j}F, where K is defined above. Thus, the consecutive gear ratios in the branch associated with r, are r„ r.K jK - and those ratios in the branch associated with r₂ are r₂, r₂K^{J> r} ₂ ^K<> ^{• • •}

It is an additional idea of this invention to utilize the speed ratios which are available by engaging two clutches of the output transmission in combination with one clutch of the input transmission. This increases the number of "gears" available for a given total number of clutches with respect to conventional countershaft transmissions. This also allows for a shift sequence with single clutch swap shifting.

It is an additional idea of this invention to make use of the forward-reverse symmetry of the input transmission and the feature of engaging two clutches of the output transmission simultaneously as described above to provide a powershift transmission system with the unique feature of single clutch swap shifting for all sequential shifts and skip shifts. For a "range shift" (meaning the sequential shift into a "gear" in which two output clutches are engaged), the single clutch swap shift is accomplished by matching the ratios in the output transmission and in the input transmission to the planetary system such that the speed ratios provided by the engagement of two output clutches and one input clutch (F) falls in between the speed ratios provided by the engagement of one of the two output clutches combined with two input clutches and (in between) the engagement of the other of the two output clutches combined with the same two input clutches. Thus the engagement of the output clutches 1 and 2 combined with the input clutch F provides a speed ratio in between the engagement of output clutch 1 combined with input clutches F and f, and the engagement of output clutch 2 combined with the same input clutches F and f. Similarly, F 2 3 falls between F 2 r and F 3 r.

To show the versatility of the concept of this invention, four variations of transmission for different applications are shown in Figures 1, 2, 3 and 4 with the corresponding Charts 1, 2, 3 and 4.

While the present invention has been described in conjunction with a specific embodiment, it is understood that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, this invention is intended to embrace all such alternatives, modifications and variations which fall within the spirit and scope of this invention.

General Description of the Continuously Variable (Hydrostatic) Options

In the description below the continuously variable element is referred to as the hydrostatic transmission. It is understood that other continuously variable system such as electrical generator-motor sets or variable friction drives could be used in place of hydrostatic units.

Two hydrostatic options are described below:

(1) Add-on option (PCVT):

A low cost option requiring relatively small hydrostatic units with minor changes on the transmission to install the units provides continuous variability over two ranges of operating speeds, one range from a certain low speed to maximum speed at fill power capacity and the other from a certain low reverse speed through zero to a certain low forward speed at full tractive load capacity. The first range requires the gradual engagement of a master clutch to start the vehicle motion, if the startup load is higher than say 53% of the vehicle weight. (53% of the weight is the amount for a specific example shown on Chart 1H line PH 1, 2) After the master clutch is fully engaged continuous variability over the full hydromechanical range from a certain low speed to maximum speed is available at full load or full power capacity. For the second range there are gear selections

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SUBSTΓΠΠΈ SHEET (RULE 26) available which provide full load continuously variable capacity from a certain low reverse speed through zero to a certain low forward speed, but the vehicle must be stopped to shift from these low speed gear selections to the gear selection for the first range. On Chart 1H the gear selection for the first range are designated hydromechanical (HM) and for the second range pure hydrostatic (PH). Note a shift from the pure hydrostatic range PH 1, 2 to the hydromechanical range PM 1 or PM 2 can be made at the S_j speed of 1523.82 rpm by engaging the F clutch, which is at synchronism at this speed.

(2) Substitution option (FCVT):

Larger hydrostatic units can be added which provide full load startup capacity by gradually increasing the displacement of the variable hydrostatic unit, but due to the space limitations these units can not be used as an "add-on" feature to the standard powershift transmission.

Description of One Typical Embodiment of the PCVT

(Add-On Option)

The transmission system consists of the powershift version as described above, with the addition of an continuously variable transmission, installed such that the input member S_j to the planetary system can be selectively connected to the engine through this continuously variable transmission

In the description below a specific transmission system (shown in Figure 1H, Chart 1H and Layout 1H) is described for simplification. It is understood, however, that the invention is not limited to this specific example.

The system has two modes of operations: The mechanical powershift mode and the hydrostatic mode. The mechanical powershift mode is described above and will not be described here.

The hydrostatic mode functions in the following manner. The input transmission of this system has two sets of three clutches. One set, denoted F, B, and Rev, selectively connects the input shaft to the R shaft through various gears, and the other set, denoted f, b, rev, selectively connects the input shaft to the Sj shaft through various gears. This set, f, b, rev, is inactive in the hydrostatic mode. In its place a fixed displacement hydrostatic unit (M) is connected to the Sj shaft by moving the shift collar (HM) rightward, and a variable displacement hydrostatic unit (P) is connected to the reverse shaft by moving the shift collar (HP) rightward.

The compound planetary system is described above on pages 4,5 and 6.

In the following description the flow of power may be positive or negative. The input transmission absorbs engine power through the input shaft, transmitting power selectively through one of a set of clutches (F or REV) to the first input member R of the compound planetary.

The clutch (F) is mounted on the input shaft to selectively drive the ring gear R, via a gear set 32(F) to 42.

The clutch (REV) is mounted on the reverse shaft. This shaft is driven through a 46 to 46r gear set from the input shaft. The reverse shaft is located such that the 32(Rev) gear is in mesh with the 42 gear. Thus the selective engagement of the REV clutch will drive the ring gear R correspondingly in the opposite direction at the same speed as the F clutch. In addition to the two clutches (F and REV), there is the clutch B. Engagement of B will stop the ring gear R from rotation.

The sun gear S_t is driven by the hydrostatic transmission at a variable speed from a certain maximum reverse speed to a certain maximum forward speed.

The output transmission absorbs power selectively through two shafts S₂ and C. The clutches mounted on the C-shaft and on the output shaft, provide two selective gear ratios from S₂ to the output shaft and three selective gear ratios from C to the output shaft. The even numbered clutches 2 and 4 are selectively connecting the S₂ shaft to the output shaft at ratios of 19(2) to 67(2),and 36(4) to 46(4), respectively. The odd numbered clutches 1, 3 and 5 are selectively connecting the C shaft to the output shaft at ratios of 19(1) to 67(1), 36(3) to 46(3) and 56(5) to 26(5), respectively.

To establish a connection from the engine to the output shaft of the output transmission either, one of the input clutches (F, B, or REV) plus the hydrostatic transmission in addition to one of the output clutches must be connected, or, two output

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SUBSTΠΓUTE SHEET (RULE 26) clutches must be engaged plus either the hydrostatic transmission or one of the input clutches (F or REV).

Thus, there are four modes of operation:

1. The low speed, pure hydrostatic (PH) mode with the clutch B engaged has five ranges, each providing continuous variability from a certain maximum reverse speed through zero speed to the same maximum forward speed as the hydrostatic transmission is varied from a maximum reverse speed through zero speed to the same maximum forward speed. To initially start the vehicle motion in this mode the clutch B and the output clutch for the particular maximum end speed are engaged after the hydrostatic transmission has been set to neutral (zero speed). Now the hydrostatic transmission can be moved to forward or reverse at any desired rate.

2. The normal hydromechanical (HM) forward speed mode with the clutch F engaged has five ranges, each providing continuous variability from a certain minimum forward speed to a certain maximum forward speed as the hydrostatic transmission ratio is varied from a maximum speed in one direction through zero speed to a maximum speed in the other direction. To provide continuous variability over the total normal forward speed range a shift in the range transmission is made at the point of synchronism of two adjacent clutches. (The point of synchronism is the hydrostatic speed at which either of two output clutches provide the same system output speed.) Thus, starting with clutch 1 engaged, the hydrostatic transmission is varied from a maximum reverse speed through zero speed to a certain forward speed at which the relative speed in the friction elements of the clutch 2 is zero. At this point the shift from clutch 1 to clutch 2 is made. To further increase the vehicle speed the hydrostatic transmission is varied from the shiftpoint-speed back through zero to a certain reverse speed at which synchronous speed in clutch 3 is reached. At this point the shift from clutch 2 to clutch 3 is made. To further increase the vehicle speed the hydrostatic transmission is varied from the shiftpoint-speed back through zero to a certain forward speed, at which another range shift can be made at

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SUBSTΓΠΠΈ SHEET (RULE 26) synchronism. From this progression it follows that the total vehicle speed range is continuously variable. It is assumed that sensors linked to a computer will sense the shiftpoint and perform the shift automatically. To initially start the vehicle motion a certain vehicle speed up to a certain maximum is preselected by the operator. Based on this selection the computer will set the hydrostatic unit, engage the F clutch and select the applicable output clutch (1 or 2). The output clutch pressure will be automatically modulated at a certain rate to provide a smooth transition from standstill to the preselected speed. Alternately the operator can override the automatic rate of modulation by pushing the clutch pedal to control the rate of clutch engagement at will.

3. The normal HM reverse speed mode with the clutch REV engaged in place of the clutch F mirrors the normal forward speed mode.

4. Two output clutches engaged with the hydrostatic transmission driving the input in the PH mode: There are 6 combinations of two output clutches engaged providing 6 continuously variable ranges from a maximum vehicle reverse speed through zero to a maximum vehicle forward speed. To initially start the vehicle motion in this mode both clutches for the particular maximum end speed are engaged after the hydrostatic transmission has been set to neutral (zero speed). Now the hydrostatic transmission can be moved into forward or reverse at any desired rate.

The Chart 1H shows the various speeds within the transmission system at various input conditions.

Column 1 shows the mode of operation, either PH or HM. The PH modes provide an continuously variable range from the maximum vehicle forward speed, indicated in column 8, through zero to the same maximum vehicle reverse speed. The HM modes provide continuous variability from the lowest speed (2.93 kph) to the highest speed (40.95 kph), however, range shifts are required at the shift points.

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SUBSTΓΓUTE SHEET (RULE 26) Column 2 indicates these shift points at the speeds wherever one or another output clutch is shown on the same line. In order to provide reverse speeds in the hydromechanical mode the reverse clutch REV must be engaged in place of the forward clutch F.

Column 3 shows the speeds of the _t shaft (fixed hydrostatic unit) required to provide the output speeds shown in column 7. The speed of the fixed unit M is varied by changing the output flow of the variable unit P. In the specific example the variable hydrostatic unit P connected to the reverse shaft has the same maximum displacement per revolution as the fixed hydrostatic unit M. Since the variable unit runs at engine speed, the fixed unit M runs at about 90% of engine speed at maximum hydrostatic pressure (10% of the speed is lost due to leakage) Thus the maximum speeds shown in column 3 are at 1800 rpm. Note: the shiftpoint speeds are at about 1500 rpm. It is assumed that speed sensors linked to a computer will perform the shift, thus the operator will not be aware of the change from one range to the next.

Columns 4 through 6 show the speeds of the members in the planetary system.

Column 9 shows the ratio of the available drawbar pull to the traction limit of the machine with sufficiently large hydrostatic units to transmit full engine power in the HM mode. The PH modes, however, show relatively low ratios. Only at maximum vehicle speeds of less than 3.14 kph is the pull to traction ratio greater than 1. This implies that a synchronous shift from the PH mode to the HM mode can not be made at maximum tractive load since this shift must be made from the clutch selection 1, 2. This selection (1, 2, column 2 in the chart 1) only provides a pull of 53% (column 9) of traction. Therefore a high energy clutch must be gradually engaged to start the vehicle motion in a preselected hydromechanical range whenever the ratio of pull to traction is greater than .53. Thus, if there is no need to pick up the load hydrostatically from standstill of the vehicle, then a small hydrostatic transmission is sufficient. Since large clutches with modulation capability are required for the powershift version of the transmission system they can also be utilized as energy absorbing clutches for the hydrostatic version to start the vehicle motion by modulation.

Column 10 shows the ratio of the available drawbar pull to the traction limit with sufficiently large hydrostatic units to provide a ratio of 1.30 in the pure hydrostatic selection 1,2. From this selection a synchronous shift can be made at 1523.81 rpm by engaging the

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SUBSTΓΓUTE SHEET (RULE 26) clutch F and then disengaging the clutch 1. Thus a continuously variable transmission (CVT) results.

The Layout 1H shows a realistic gear, shaft, bearing and housing arrangement for the transmission described on Fig 1 and Chart 1.

Description of One Typical Embodiment of the FCVT

(Substitution option )

In the description below a specific CVT (shown on Figure 2H, chart 2H, and Layout 2H) is described for simplification. It is understood, however, that the invention is not limited to this specific example.

In this system the f, rev, b, and the B clutches with their corresponding gears have been removed from the input transmission of the powershift version. In their place a gear set (22, 34) to drive the hydrostatic unit M has been added and the gear ratio (36, 55) to drive the reverse shaft has been added, plus the REV gear 22REV has been added. In effect the displacement of the hydrostatic units has been increased due to their higher operating speed with respect to the units mounted as shown on Figure 1. Additionally the displacement per revolution must be increased to provide sufficient hydrostatic torque for the traction limit of the vehicle.

Chart 2H shows that the CVT can operate at any speed from 0 to 40.95 kph. There are 4 shift points as indicated in column 2 wherever one or another output clutch are shown on the same line.

At these shift points a shift between the two clutches shown on the particular line can be made at synchronism. In other words either clutch will provide the same vehicle speed at the speed of the sun gear Si indicated on the line (column 3).

Since the shifts can be made at synchronism all friction clutches could be replaced by jaw clutches. The choice becomes a matter of economics including the control system which must be more accurate to sense the speeds of synchronism. The friction clutches are more forgiving than the jaw clutches, however, they generate higher power losses thus affecting the efficiency adversely. The friction clutches can be made with fewer discs at higher clamping forces and lower cooling flow, since they need not absorb high energy and therefore the losses can be minimized.

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SUBSTΠTJTE SHEET (RULE 26) The last column 10 on Chart 2H indicates the effect of the larger hydrostatic units in the pure hydrostatic (PM) modes with respect to column 9 (smaller units). In column 10 the ratio of pull available to traction is greater than 1 (1.30), when the clutches 1 and 2 are engaged, thus the vehicle can reach the shiftpoint under the highest normal load condition. If for some reason the traction is unusually high, say the tires are frozen to the ground, the pure hydrostatic selection 1 4 can be made which will more than double the available pull (2.16) , however, no synchronous shift can be made from this selection. The vehicle must be stopped, and 1, 2 must be selected for continuous variability from zero speed.

The Layout 2H shows a realistic gear and bearing arrangement to provide for higher speeds for the hydrostatic units.

General Comments on Hydrostatic Options

It is an additional idea of this invention to design the input transmission such that the hydrostatic branch can be added as an option to a powershift transmission with either the hydrostatic mode or the powershift mode being selectable by the operator as described above.

It is an additional idea to use a modulated clutch which is already present in the powershift version to start the vehicle motion from standstill rather than the hydrostatic transmission whenever the transmission system is started in the hydromechanical mode at high startup loads. Thus the hydrostatic units can be kept small since the high startup torque is not required making it physically possible to provide selectable modes of operation as described in the paragraph above.

It is an additional idea to provide a full continuously variable transmission (FCVT) from maximum reverse through zero to maximum forward speed by using sufficiently large hydrostatic units without changes to the housings, planetary system and output transmission. This is possible because there exist synchronous speeds for the F clutch while operating in the pure hydrostatic mode at a point where the sun gear speed S_j is equal to the ring gear speed.

Features in the arrangement of clutches, gears, shafts and bearings

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SUBSTΠ ΠΈ SHEET (RULE 26) System for a vehicle with rear mounted transmission

The Layout 1H shows a cross section of the transmission system for a vehicle design in which the transmission system is mounted to the rear frame with a relatively large space available at the input side of the transmission, thus the axial space available for the input transmission allows the use of pairs of clutches and the mounting of optional hydrostatic units at the input side of the transmission system. Further more this type of vehicle design requires the Power Take Off drive to be located across the top of the transmission with a pump drive to be located at the side of the transmission.

The input transmission has two identical clutch-gear assemblies for the forward and reverse shafts providing a cost advantage. No reverse idler gear is required, again a cost advantage. The clutches are arranged such that the high feedback speed on the 22f and 22rev gears does not affect the clutch actuation, thus no dump valves are required which are normally used to deal with high clutch speeds. The hydrostatic transmission is easily attachable to two shafts, requiring no extra gears, shafts or bearings.

The planetary system is arranged such that the input sun gear S, and the carrier C are floating, with the ring gear semifloating off one bearing support BF on the left side. This floatation provides good load distribution over all the planets. Only the output sun gear S₂ is radially fixed on a bearing.

The output transmission is arranged such that the two high energy clutches (master clutches 1 and 2) with a large friction surface area and dual cooling flow are located on the output shaft where the torque is high. The low energy, low torque clutches 3 and 5 are located on one of the input shafts (C). The remaining clutch 4 uses the otherwise "dead" space on the output shaft below the bearing mounting of the S₂ shaft. The three clutches 1, 2 and 4, located on the output shaft, are designed such that the actuating piston is rotating with the clutch gear to eliminate the effect of the high speed of the output shaft in the higher gear selections. This clutch design is described in the provisional application Serial No. 60/071661 of Clutch Assembly For Transmission on January 16, 1998.

The input shaft (S₂ shaft) of the output transmission is mounted on two bearings. The gears 19(2) and 36(4) are cantilevered on the right side and the sun gear S₂ is cantilevered on the left side of the shaft (S₂ shaft). An extension of the one input shaft (S₂

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SUBSTΓΓUTE SHEET (RULE 26) shaft) acts as the bearing mount for the other input shaft (C shaft). This eliminates the need for a bearing mount attached to the housing, which would require additional axial space and cause an assembly problem.

The 38a accessory drive gear is coupled to the input shaft to rotate at engine speed. It is in mesh with the 38i idler gear, which drives the PTOin shaft and which also is in mesh with the 29p pump gear (not shown on the Layout but indicated on Figure IH). The PTOin shaft drives a gear 33 located at the rear of the transmission assembly where it is in mesh with the PTO output gear 30 which in turn is connected to the PTOout shaft. Note, this arrangement makes it possible to bring the engine speed physically around the range transmission back to the center location of the assembly at the rear of the transmission in line with a PTO clutch and gear reduction (not shown).

The park brake is located on the output shaft below the pressure control manifold for the clutches 3 and 5. Again this axial space would otherwise not be utilized.

The mechanical front drive clutch (MFD) is located as far to the rear as possible to allow for maximum ground clearance at the center of the tractor.

System for a vehicle with a front mounted transmission.

In Figure 2, Chart 2 and Layout 2, a transmission system shown for a vehicle design in which the transmission is mounted towards the engine side allowing relatively small axial space for the input transmission. Tn this design it is possible to arrange the gear system such that one single clutch per shaft is used for the two reverse clutches and one forward clutch. Also the optional hydrostatic units are moved towards the output side of the transmission. This design requires the Power Take Off to be located at the bottom of the transmission system, therefore, a geartrain from the input shaft to the bottom is required, which fits in perfectly with the arrangement of gears for the input transmission.

The input transmission is comprised of an input shaft on which the clutch f is mounted said clutch f selectively connecting the shaft Sj to the input shaft through gears 22f and 55, is further comprised of one reverse shaft (rev shaft) on which the rev clutch is mounted said rev clutch selectively connecting the Sj shaft to the input shaft through gears 321 to 32r to 22r to 55, is further comprised of one other reverse shaft on which the REV clutch is mounted ,said REV clutch selectively connecting the R shaft to the input shaft through gears 321 to 32Ri to 32Ro to 43R, is further comprised of one hollow R shaft concentric to the S, shaft on which the F clutch is mounted said F clutch selectively connecting the input shaft to the R shaft through gears 321 to 43F, is further comprised of one b clutch which selectively stops the S, shaft from rotation and is further comprised of one B clutch which selectively stops the R shaft from rotation. The S, shaft is connected to the sungear of the planetary system and the R shaft is connected to the ring gear of the planetary system.

The transmission is further comprised of a Front Drive Shaft on which the Front Wheel drive Clutch, the Park Brake and the idler cluster gear 28-38 is mounted. The Front Wheel drive Clutch selectively connects the front wheels to the output shaft, the Park Brake selectively stops the output shaft from rotation and the idler cluster gear connects the input shaft to the PTO shaft through gears 321 to 43F to 38 to 28 to 51.

The compound planetary system and the output transmission are arranged in the same manner as described above under System for vehicle with rear mounted transmission.

The optional hydrostatic transmission is mounted at the rear of the transmission such that the fixed displacement unit M is selectively connectable to the H shaft which is located concentrically inside the C shaft and attached to the sungear 18, and such that the variable displacement unit P is selectively connectable to a shaft driven by a gear from the PTO shaft. The hydrostatic units M and P are hydraulically interconnected by fluid conduits. Chart 2 and Layout 2 show a realistic gear, shaft, bearing and housing arrangement for the front mounted transmission.

General comments on features in the arrangement of clutches, gears, shafts and bearings

From the description of the Layout IH on page 17 and of Layout 2 on page 18 it is apparent that several ideas are unique, including but not limited to the following:

1. The arrangement of clutches, gears and shafts in the input transmission which makes it possible to use identical parts for the forward and reverse clutch assemblies, and also makes it possible to attach the hydrostatic units optionally, without the addition of gears, bearings and other major parts. ( Layout IH )

2. The arrangement of clutches gears and shafts in the input transmission which make it possible to minimize the axial space required for the input transmission and to provide for a Power Take Off ( Layout 2 )

3. The mounting of the planetary system, providing flotation of the sun gear S, and the carrier C in addition to providing stability through the radially fixed sun gear S₂ in combination with the semifloating-floating ring gear R, which is supported on one side by the bearing BF.

4. The mounting of the S₂ shaft on two bearings with cantilevered mounting of gears on each side in addition to provide a bearing mount for the C shaft through a cantilevered extension of the S₂ shaft.

5. The arrangement of gears, clutches and shafts in the output transmission providing for a maximum utilization of axial space for essentially a five speed package plus a park brake on two centers.

6. The arrangement of the pump drive and the PTO which utilizes the necessary idler gear 38i for two purposes: first to bring the pump drive gear 27p far enough out to provide clearance for the pump and second to provide a connection for the PTOin shaft. (Note that the direction of rotation of the PTOout shaft requires the idler gear.)

While the present invention has been described in conjunction with a specific embodiment, it is understood that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, this invention is intended to embrace all such alternatives, modifications and variations which fall within the spirit and scope of this invention.

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SUBSTΠTΠΈ SHEET (RULE 26)

Claims

WHAT IS CLAIMED IS:

1. A mechanical power transmission system for an engine or motor driven vehicle comprising: an input transmission, a compound planetary transmission, and an output transmission, the said compound planetary system being comprised of two input means and two output means, the said input transmission being comprised of one input means, connected to the engine or motor of a vehicle, and two output means connected to two input means of the said compound planetary system,the said output transmission being comprised of two input means connected to the two output means of the said compound planetary system and one output means connected though gearing to the wheels of the vehicle or to any other mechanism to be driven by a motoring device at various speed ratios.

2. A mechanical transmission system, in which the input transmission absorbs engine power through an input means (the input shaft), dividing the power selectively at various proportions for delivery to two output means (R and Sj shafts), said output means to deliver power at certain proportions to a compound planetary system having two means (R and S,) to absorb power and said planetary system to combine the power for delivery through either of two means (C) or (S₂) to an output transmission, said output transmission having two means to absorb power selectively at various gear ratios through one input means (S₂ shaft) or another input means (C shaft), transmitting the power to an output means respectively at a variety of rotational speeds relative to the rotational speed of the engine, wherein the power flow may be positive or negative.

3. A transmission system, in which the input transmission absorbs power from an engine through an input means (input shaft), transmitting the power selectively at various gear ratios to either the first output means (R shaft) with the second output means (S_j shaft) stopped, or transmitting the power to the second output mean (S_j shaft) with the first output means (R shaft) stopped, either of the said output means respectively to deliver power to a compound planetary system, said compound planetary system to absorb power respectively through either one input means (R) or the other input means (S_j), transmitting the power to either one or the other of two output means (C or S₂) said output means to

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SUBST╬ô╬ôUTE SHEET (RULE 26) deliver power to an output transmission said output transmission having two means to absorb power selectively through one input means (S₂ shaft) or another input means (C shaft), transmitting the power selectively at various gear ratios to an output means respectively at a variety of rotational speeds relative to the rotational speed of the engine, wherein the power flow may be positive or negative.

4. A transmission system, in which the input transmission absorbs power from the engine, transmitting the power selectively to the first output means (the R shaft)), the said first output means to deliver power to a compound planetary system, said compound planetary system to absorb power respectively through the first input means (R)), dividing the power at certain ratios for delivery to two output means (C and S₂), said output means to deliver power to an output transmission having two means (C shaft and S₂ shaft) to absorb power at certain ratios and to combine the power for selective delivery at various gear ratios to an output means (output shaft) providing a variety of rotational speeds relative to the rotational speed of the engine, wherein the power flow may be positive or negative.

5. A transmission system, in which the input transmission absorbs power from the engine, transmitting the power selectively to the second output means (the S, shaft), the said second output means to deliver power to a compound planetary system, said compound planetary system to absorb power respectively through the second input means (S_j), dividing the power at certain ratios for delivery to two output means (C and S₂) said output means to deliver power to an output transmission having two means (C shaft and S₂ shaft) to absorb power at certain ratios and to combine the power for selective delivery at various gear ratios to an output means (output shaft) providing a variety of rotational speeds relative to the rotational speed of the engine, wherein the power flow may be positive or negative.

6. A transmission system of claims 2 through 5, in which the compound planetary system is comprised of two sets of planet systems (P_j and P₀) each having a ring gear, a sun gear and planet gears which are rotatably supported by sets of shafts anchored in planet

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SUBST╬á╬ôUTE SHEET (RULE 26) carriers, the planet system Pj being a simple planetary, where each planet gear is in mesh with the sun gear and with the ring gear, the system P₀ being a double planetary where one set of planets is in mesh with the sun gear and with the other set of planets and the said other set of planets is in mesh with the ring gear, where the ring gear R of P_{ is connected to the ring gear of set P₀ and where the planet carrier C of P_; is connected to the carrier of P₀, the ring gear R and the sun gear S_j of the Pj being the two input members of the planetary system and the carrier C and the sun gear S₂ of P₀ being the two output members of the planetary system.

7. A transmission system of claims 2 through 5 in which the compound planetary system is comprised of two sets of planet systems (P; and P₀), P₍ having a ring gear, and both P_j and P₀ having a sun gear and planet gears which are rotatably supported by sets of shafts anchored in a planet carrier, the planet system Pj being a simple planetary, where each planet gear is in mesh with the sun gear and with the ring gear, and the system P₀ being a double planetary, where one set of planets (ps) is in mesh with the sun gear and with the other set of planets (pr), the planets (pr) of P₀ being connected to the planets of P_; in pairs and rotatably mounted on the same set of shafts which are anchored in the common carrier, the ring gear R and the sun gear Sj of P_j being the two input members of the planetary system and the carrier C and the sun gear S₂ of P₀ being the two output members of the planetary system.

8. A transmission system of claims 2 through 5 in which the compound planetary system is comprised of two sets of planet systems (P; and P₀) each having a ring gear, a sun gear and planet gears which are rotatably supported by sets of shafts anchored in planet carriers, the planet system Pj and P₀ being simple planetaries, where each planet gear is in mesh with the sun gear and with the ring gear respectively, where the ring gear R of P_j is connected to the planet carrier of P₀ and the planet carrier C of Pj is connected to the ring gear of P_Q, the ring gear R and the sun gear S, of the Pj being the two input members of the planetary system and the ring gear C and the sun gear S₂ of P₀ being the two output members of the planetary system.

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SUBSTΓΓUTE SHEET (RULE 26)

9. A transmission system of claims 2 through 5 in which the compound planetary system is comprised of two sets of planet systems (P_j and P₀) each having a ring gear, a sun gear and planet gears which are rotatably supported by sets of shafts anchored in planet carriers, the planet system Pj and P₀ being double planetary systems where one set of planets is in mesh with the sun gear and with the other set of planets and the other set of planets is in mesh with the ring gear respectively, where the ring gear R of Pj is connected to the ring gear of set P₀ and where the planet carrier C of Pj is connected to the sun gear S₂ of P_╬╕5 the ring gear R and the sun gear Sj of the P; being the two input members of the planetary system and the carrier C and the sun gear S₂ of P₀ being the two output members of the planetary system.

10. A transmission system of claims 2 through 5 in which the compound planetary system is comprised of two sets of planet systems (Pj and P₀) each having a ring gear, a sun gear and planet gears which are rotatably supported by sets of shafts anchored in planet carriers, the planet system Pj and P₀ being simple planetaries, where each planet gear is in mesh with the sun gear and with the ring gear respectively, where the ring gear R of P_{ is connected to the ring gear of P₀ and the sun gear of P_f is connected to the sun gear of P₀, the ring gear R and the sun gear Sj of the Pj being the two input members of the planetary system and the ring gear C and the sun gear S₂ of P₀ being the two output members of the planetary system.

11. A transmission system of claims 2 through 5 in which the compound planetary system is comprised of two sets of planet systems (P_j and P₀) each having a ring gear, a sun gear and planet gears which are rotatably supported by sets of shafts anchored in planet carriers, the planet system P₀ being a simple planetary, where each planet gear is in mesh with the sun gear and with the ring gear, the system P_{ being a double planetary where one set of planets is in mesh with the sun gear and with the other set of planets and the other set of planets is in mesh with the ring gear, where the ring gear R of P_j is connected to the planet carrier of set P₀ and where the planet carrier of P_j is connected to the sun gear of P₀, the ring gear R and the sun gear Sj of the P; being the two input members of the planetary

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SUBST╬ô╬ôUTE SHEET (RULE 26) system and the ring gear C and the sun gear S₂ of P₀ being the two output members of the planetary system.

12. A transmission system of claims 2 through 5 in which the compound planetary system is comprised of two sets of planet systems (Pi and P₀) each having a ring gear, a sun gear and planet gears which are rotatably supported by sets of shafts anchored in planet carriers, the planet system Pj being a simple planetary, where each planet gear is in mesh with the sun gear and with the ring gear, the system P₀ being a double planetary where one set of planets is in mesh with the sun gear and with the other set of planets is in mesh with the ring gear, where the ring gear R of Pj is connected to the sun gear of set P₀ and where the planet carrier C of P_j is connected to the ring gear of P_╬╕5 the planet carrier R and the sun gear S_j of the P; being the two input members of the planetary system and the carrier C and the sun gear S₂ of P₀ being the two output members of the planetary system.

13. A transmission system of claims 2 through 5 in which the compound planetary system is comprised of two sets of planet systems Pj & P₀) each having a ring gear, a sun gear and planet gears which are rotatably supported by sets of shafts anchored in planet carriers, the planet system P_; and P_Q being simple planetaries, where each planet gear is in mesh with the sun gear and with the ring gear respectively, where the planet carrier R of Pj is connected to the ring gear of P_D and the sun gear of P_{ is connected to the sun gear of P₀, the planet carrier R and the sun gear S, of the P; being the two input members of the planetary system and the planet carrier C of P₀ and the ring gear S₂ of P_; being the two output members of the planetary system.

14. A transmission system of claims 2 through 5 in which the compound planetary system is comprised of two sets of planet systems (Pj & P₀) each having a ring gear, a sun gear and planet gears which are rotatably supported by sets of shafts anchored in planet carriers, the planet system Pj and P₀ being simple planetaries, where each planet gear is in mesh with the sun gear and with the ring gear respectively, where the sun gear Sj of P; is connected to the sun gear of P₀ and the planet carrier of Pj is connected to the planet carrier of P₀, the ring gear R and the sun gear Sj of the Pj being the two input members of the planetary system and the ring gear S₂ and the planet carrier C of P₀ being the two output members of the planetary system.

15. A transmission system of claims 2 through 5 in which the compound planetary system is comprised of two sets of planet systems (Pj & P₀) each having a ring gear, a sun gear and planet gears which are rotatably supported by sets of shafts anchored in planet carriers, the planet system P_; being a simple planetary, where each planet gear is in mesh with the sun gear and with the ring gear, the system P₀ being a double planetary where one set of planets is in mesh with the sun gear and with the other set of planets and the other set of planets is in mesh with the ring gear, where the carrier C of P_j is connected to the carrier of set P₀ and where the sun gear Sj of Pj is connected to the ring gear of P_Q, the ring gear R and the sun gear Sj of the Pj being the two input members of the planetary system and the carrier C and the sun gear S₂ of P₀ being the two output members of the planetary system.

16. A transmission system of claim 2 through 5, in which the input transmission is comprised of three clutches (F, B and REV) selectively engagable to connect the first input member (R) of the planetary system to the input shaft of the said input transmission at a certain forward speed ratio through F, or at a certain essentially equal reverse speed ratio through REV and to connect said first input member R to the housing through clutch B stopping rotation of the said input member R, the said input transmission further being comprised of an odd number N_s of clutches selectively engageable to connect the second input member (Sj) of the planetary system to the input shaft of said input transmission at a number (N,-l)/2 of speed ratios in forward and at the same number (N,-l)/2 of speeds in reverse at essentially equal ratios as the forward speeds, plus one clutch (b) to connect the said second input member S j to the housing stopping rotation of the said second input member S_b said second input member (S,) being that input member of the planetary system which changes speed whenever a sequential shift is made in the normal operating range, normal operating range being that range of selectable ground speeds in which the said first input member (R) of the planetary system remains at constant speed with respect to the engine speed whenever a sequential shift is made.

17. A transmission system of claim 2 through 5, in which the input transmission is comprised of three clutches (F, B and REV) selectively engagable to connect the first input member (R) of the planetary system to the input shaft of the said input transmission at a certain forward speed ratio through F, or at a certain essentially equal reverse speed ratio through REV and to connect said first input member R to the housing through clutch B stopping rotation of the said input member R, the said input transmission further being comprised of an even number N_s of clutches selectively engageable to connect the second input member (Sj) of the planetary system to the input shaft of said input transmission at a number (NJ/2 of speed ratios in forward and at the same number (N,)/2 of speeds in reverse at essentially equal ratios as the forward speeds, said second input member (Sj) being that input member of the planetary system which changes speed whenever a sequential shift is made in the normal operating range, normal operating range being that range of selectable ground speeds in which the said first input member (R) of the planetary system remains at constant speed with respect to the engine speed whenever a sequential shift is made.

18. A transmission system of claims 16 and 17 in which the stopping clutch (B) and reverse clutch (REV) are omitted.

19. A transmission system of claims 16 and 17 in which the stopping clutch (B) is omitted.

20. A transmission system of claims 16 and 17 in which the reverse clutch (REV) is omitted.

21. A transmission system of claims 2 through 17, in which the output transmission is comprised of two sets of equal number of clutches selectively engageable to connect the output shaft of said output transmission at certain ratios to the output members of the planetary system, one set of the said clutches connecting the said output shaft to the first output member (C) of the planetary system at various gear ratios and the other set of said clutches connecting the said output shaft to the second output member (S_) of the planetary system at various gear ratios, the said first output member (C) of the planetary system

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SUBSTΓΓUTE SHEET (RULE 26) being that member which increases in speed as the second input member (S_t) of the planetary system increases in speed while the first input member (R) of the planetary system is at constant speed, and the said second output member (S_) of the planetary system being that member which decreases is speed as the said second input member (S,) of the planetary system increases in speed while the said first input member (R) of the planetary system is at constant speed.

22. A transmission system of claim 21 in which the output transmission is comprised of two sets of clutches in which the number of clutches in one set is one fewer than in the other set.

23. A transmission system of claims 2 through 17, in which all gear ratios of mating gear sets within the compound planetary system are such that the rate of change in speed of the first output member (C) of the planetary system with respect to the second input member (Sj) of the planetary system is essentially equal to the rate of change in speed of the second output member (S^of the planetary system with respect to the second input member (Sj) of the planetary system multiplied by the number minus (r,/r₂) multiplied by K , with the first input member (R) of the planetary system at constant speed as expressed in the following differential equation

^r2 d 5, ^{"K r,} d 5, ' = constant,

and are such that the speed of the second output member (S₂)of the planetary system multiplied by r₂ is essentially equal to the speed of the first output member (C) of the planetary system multiplied by r, multiplied by K, with the second input member (Sj) at zero speed and the first input member (R) at constant speed, as expressed in the following equation:

where

^ r, = ^r, at -S^ O ,

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SUBST╬ô╬ôUTE SHEET (RULE 26) S₂ is the speed of the second output member (S₂) of the planetary system which decreases in speed as the second input member (S,) of the planetary system increases in speed while the first input member (R) of the planetary system is at constant speed,

r₂ is the lowest selectable gear ratio between the sun gear S₂ and the output shaft of the output transmission ,

is the speed of the first output member (C) of the planetary system which increases in speed as the second input member (Sj) of the planetary system increases in speed while the first input member (R) of the planetary system is at constant speed,

r, is the lowest selectable gear ratio between the carrier C and the output shaft of the output transmission,

S_x is the speed of the second input member (S,) of the planetary system, which is selectively connectable to the engine at one or more ratios in forward and reverse, said second input member (S_j) being that input member of the planetary system which changes speed whenever a sequential shift is made in the normal operating range, normal operating range being that range of selectable ground speeds in which the said first input member (R) of the planetary system remains at constant speed with respect to the engine,

J is the speed of the first input member (R) of the planetary system, which remains selectively connected to the engine at a certain gear ratio either in forward or in reverse, whenever the transmission is operating in the normal operating range either in forward or reverse respectively, and where

K is a constant calculated by the following equation:

^κ-©"^pfcτ ri- where

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SUBSTΠΓUTE SHEET (RULE 26) H is the highest desired rated output speed of the transmission system,

L is the lowest desired rated output speed to be attained in the normal operating range said normal operating range being the range of selectable groung speeds in which the first input member (R) of the planetary system remains connected through a gear ratio to the engine,

N₀ is the number clutches in the output transmission,

N, is the number of clutches in the set which selectively connects the engine through gear ratios to second input member (Sj) of the planetary system or stops said second input member from rotation.

24. A transmission system of claim 2 through 5 with an input transmission having an odd number of selectable connections from the input shaft of said input transmission to the second input member (S,) of the planetary system, in which the gear ratios of each selectable connection, including the one where said second input member (Sj) is stopped, are such that the geometric steps in the output speed of the transmission system from one gear selection to the next in a certain interval are essentially equal, said interval being defined as the range from the gear selection in which two clutches in the output transmission are engaged, to that higher gear selection in which the second input member (S_j) of the planetary is stopped, geometric step being defined as the factor with which a output speed of one gear selection is multiplied to obtain the speed of the next higher gear selection, said second input member (S_j) being that input member of the planetary system which changes speed whenever a sequential shift is made in the normal operating range, normal operating range being that range of selectable gears in which the first input member (R) of the planetary system remains at constant speed with respect to the engine..

25. A transmission system of claim 2 through 5 with an input transmission having an even number of selectable connections from the input shaft of said input transmission to the second member (S_j) of the planetary system, in which the gear ratios of each selectable connection

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SUBSTΓΓUTE SHEET (RULE 26) are such that the geometric steps in the output speed of the transmission system from one gear selection to the next in a certain interval are essentially equal, said interval being defined as the range from the gear selection in which two clutches in the output transmission are engaged, to that higher gear selection in which the direction of the speed of the second member Sj of the planetary is changed, geometric step being defined as the factor with which a output speed of one gear selection is multiplied to obtain the speed of the next higher gear selection, said second input member (S,) being that input member of the planetary system which changes speed whenever a sequential shift is made in the normal operating range, normal operating range being that range of selectable gears in which the first input member (R) of the planetary system remains at constant speed with respect to the engine either in forward or reverse.

26. A transmission system of claims 2 through 5 and 23 with an output transmission in which the lowest gear ratio Tj selectively connectable between the first output member C of the planetary system and the output shaft, multiplied by K², is essentially equal to the next higher gear ratio r₃ selectively connectable to said member C, in which (output transmission) the again next higher gear ratio r₅ selectively connectable to said member C, if said gear ratio r_s is present, is essentially equal to the said gear ratio r₃ multiplied by K², and in which (output transmission) the lowest gear ratio r₂ selectively connectable between the second output member S₂ of the planetary system and the output shaft, multiplied by K², is essentially equal to the next higher gear ratio r₄ selectively connectable to said member S₂, in which (output transmission) the again next higher gear ratio r₆ selectively connectable to said member S₂ ,if said gear ratio r₆ is present, is essentially equal to the said gear ratio r₄ multiplied by K², where K is defined in claim 23.

27. A transmission system of claims 23 and 26 in which r is equal to x_

28. A transmission system of claims 6 through 22 , with a normal operating range , being that range, where the first member (R) of the planetary system is connected to the input shaft of the input transmission through a gear ratio, in which the ground speed selection that

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SUBS╬áTUTE SHEET (RULE 26) connects the two output members C and S₂ of the planetary system at two respective ratios (say c and s) to the output member of the output transmission, provides a ground speed that is in between the ground speeds provided by the ground speed selection that connects the second input member (Sj) of the planetary to the input member of the input transmission at a certain ratio (say f) and that connects one of the said members (C) of the planetary system to the output member of the output transmission at the same ratio (c) and (in between) the ground speed provided by the ground speed selection that connects the second input member (S_j) of the planetary to the input member of the input transmission at the same ratio (f) and that connects the other of the said members (S₂) of the planetary system to the output member of the output transmission at the same ratio (s).

29. A transmission system of claims 6 through 22, in which the sequence of clutch engagements providing sequentially higher ground speeds is such that in the normal operating range, being that range, where the first member (R) of the planetary system is connected to the input shaft of the input transmission through a gear ratio, only one clutch needs to be disengaged and only one other clutch needs to be engaged, while the other two clutches in the system remain engaged, in order to obtain the next higher ground speed.

30. A transmission system of claims 6 through 22 in which the sequence of clutch engagements providing sequentially higher ground speeds is such that in the normal operating range only one clutch needs to be disengaged and only one other clutch needs to be engaged, while the other two clutches in the system remain engaged, in order to obtain the ground speed which is one speed above the next higher speed.

31. A transmission system of claim 6 trough 22 in which ground speed selections are utilized outside the normal operating range, being that range, where the first member (R) of the planetary system is connected to the input shaft of the input transmission through a gear ratio, by simultaneous engagement of two output clutches in combination with one input clutch which connects the second input member (Sj) of the planetary system to the input member of the input transmission, the said two output clutches being one clutch of the group

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SUBSTΓΓUTE SHEET (RULE 26) of clutches connecting the output member (C ) of the planetary system to the output shaft of the output transmission and being one clutch of the group of clutches connecting the other output member (S_) of the planetary system to the output shaft of the output transmission at respective ratios.

32. A transmission system of claim 6 through 22 in which ground speed selections are utilized outside the normal operating range, being that range, where the first member (R) of the planetary system is connected to the input shaft of the input transmission through a gear ratio, by the engagement of any one output clutch in the output transmission in combination with any one input clutch which connects the second input member (S_t) of the planetary system to the input member of the input transmission and in combination with the first input member (R) stopped by the engagement of a clutch,

33. A transmission system of claims 2 through 22 in which the input transmission is comprised of an additional selectively connectable power flow path from the engine or motor to the second input member (S,) of the planetary system said power flow path being continuously variable,

34. A transmission system of claim 33 in which the continuously variable power flow path is made up of a variable displacement hydrostatic unit selectively connectable to the engine or motor and a fixed displacement hydrostatic unit selectively connectable to the second input member Sj of the planetary system the said hydrostatic units being connected by hydraulic conduits.

35. A transmission system of claims 34 in which the continuously variable power flow path covers a speed range for the second input member (S_j) of the planetary system from forward to reverse such that at or near the extreme output speeds of the hydrostatic system in forward or reverse a shift from one clutch to another clutch in the output transmission can be made at or near synchronism of the engaging clutch, synchronism being defined as the condition where the input member of the clutch is at the same speed as the output member of the same clutch.

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SUBSTΓΠΠΈ SHEET (RULE 26)

36. A transmission system of claim 35 in which the continuously variable power flow path can be added as an option to the standard powershift transmission of claims 12 through 22.

37. A transmission system of claims 36 in which the continuously variable power flow path is sufficiently large to allow full available engine power to be transmitted in the normal hydromechanical range but lacks the capacity to transmit full tractive load in the pure hydrostatic range with the two lowest speed output clutches in the output transmission engaged, hydromechanical range being that portion of the selected connections where part of the power flows through the hydrostatic system and part of the power flows through the mechanical connection and the hydrostatic range being that portion of the selected range where all the power flows through the hydrostatic system .

38. A transmission system of claim 37 in which at least one of the clutches engaged in the lowest speed hydromechamcal mode is sufficiently large to bring the vehicle from standstill to full motion under full tractive load by gradually engaging the said sufficiently large clutch.

39. A transmission system of claim 35 in which the variable transmission is sufficiently large to bring the vehicle from standstill to full motion under full tractive load by gradually increasing the displacement of the variable hydrostatic unit from zero to maximum forward or reverse in the gear selection where the two lowest speed clutches in the output transmission are engaged, thus allowing the engagement of the forward or reverse clutch at synchronism to provide full continuous variability at full load from maximum reverse speed through zero speed to maximum forward speed.

40. A transmission system of claims 6 through 22 in which the number of clutches selectively engagable to connect the input member S_x of the planetary system to either the engine or to the housing is three, one being at a certain forward ratio and the other being at a essentially equal ratio in reverse and the third stopping the said input member S_j from rotation.

41. A transmission system of claim 40 with an input transmission comprising an input shaft,

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SUBSTΓΓUTE SHEET (RULE 26) a counter shaft and two concentric output shafts ( R shaft and Sj shaft), in which two pairs of clutches are used, which said pairs may be physically equal to each other, one pair, mounted on the said input shaft, serving as the forward clutches with two forward clutch gears, and one pair, mounted on the countershaft, serving as the reverse clutches with two reverse clutch gears, the countershaft being located in the housing such that a set of gears connects the said input shaft to the said counter shaft and such that one gear connected to the said first output shaft (R shaft) is in mesh with one said forward clutch gear and one said reverse clutch gear and such that one gear connected to the second output shaft (S, shaft) is in mesh with the other said forward clutch gear and the other said reverse clutch gear, further in which each said output shafts are selectively connectable to the housing through two clutches respectively.

42. A transmission system of claim 41 in which the counter shaft is extended to provide a selectable connection to a variable displacement hydrostatic unit and in which the shaft (S_x shaft) connected to the second input member Sj of the planetary system is extended to provide a selectable connection to a fixed displacement hydrostatic unit, the two hydrostatic units being hydraulically interconnected by fluid conduits.

43. A transmission system of claim 41 in which single clutch packs are used rather than pairs, the forward clutch (f), which selectively connects the second member S_j of the planetary to the input shaft of the input transmission, being located on said input shaft, the forward clutch (F), which selectively connects the first member R of the planetary system to said input shaft, being located on a hollow first shaft (R shaft) which is concentric to the second shaft (Sj shaft) attached to the said second member S,, the reverse clutches (rev and REV) being located on two separate counter shafts, which are positioned such that one gear mounted to the said input shaft is in mesh with one gear each mounted on the two said counter shafts in addition to being in mesh with the clutch gear of the said clutch (F), said clutch gear acting as an idler gear for the Power Take Off gear train of the vehicle, the output gear of the reverse clutch rev and the output gear of the said forward clutch (f) being in mesh with a gear connected to the said second shaft (S, shaft) attached to the said second member Sj of the planetary system, said second shaft also being connected to the output of a clutch

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SUBSTΓΓUTE SHEET (RULE 26) b the engagement of which stops rotation of the said second member Sj, the output gear of the clutch REV being in mesh with a gear mounted on said hollow first shaft which is attached to the said first member R of the planetary system, said clutch F having a clutch carrier mounted to the said hollow first shaft, said carrier serving as the means to carry an additional clutch B concentric to said clutch F, said clutch B to selectively connect said first member R of the planetary system to the housing stopping the rotation of the said first member R.

44. A transmission system of claim 43 in which the second input member Sj of the planetary system is selectively connectable to a hydrostatic unit through a shaft extending from the member S, through hollow shafts which are serving as output means of the planetary system, said hydrostatic unit being connected hydraulically by fluid conduits to a variable displacement hydrostatic unit which is driven by a convenient connection to the engine or motor.

45. A transmission system of claim 6 in which the common ring gear of the two planetary gear sets of the compound planetary system is mounted through a splined carrier to a hollow shaft (R shaft) on one side, said hollow shaft being mounted through a bearing in the housing, allowing the other side to float on the gear mesh between the ring gear and the planets, the planets in turn being allowed to float on the gear mesh between the planets and the sun gears, the output sun gear S₂ being on a shaft which is radially fixed on bearings, while the input sun gear Sj is allowed to float, "to float" meaning to allow a gear to seek its own center of rotation thus insuring equal distribution of tooth load among the planet gears.

46. A transmission of claim 21 in which a shaft SS₂ attached to the second output member S₂ of the planetary system is mounted in the housing through two bearings with sufficient capacity and sufficient distance between the bearings to carry the gear load of either one of two gears plus the load of a bearing , the said loads being cantilevered off the output side of the shaft SS₂, while the sungear S₂ is cantilevered off the input side of the shaft.

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SUBSTΠTΠΈ SHEET (RULE 26)